#app{
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-color: #2486b9;
}

.box{
  position: relative;
  width: 80px;
  height: 80px;
}
.box::after,.box::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 0;
  height: 0;
  border: 50px solid transparent;
  border-top-color: #fff;
  animation: rotateA 2s  linear infinite .5s;
}
.box::before{
  transform: rotate(90deg);
  animation: rotateB 2s linear  infinite;
}

@keyframes rotateB{
  0%,25%{
    transform:rotate(90deg)
  }
  50%,75%{
    transform: rotate(270deg);
  }
  100%{
    transform:rotate(450deg)
  }
}

@keyframes rotateA{
  0%,25%{
    transform:rotate(0deg)
  }
  50%,75%{
    transform: rotate(180deg);
  }
  100%{
    transform:rotate(360deg)
  }
}